Tonight, after 70 years in showbusiness, Angela Lansbury finally gets an Oscar with her name on it. It's an honorary one, the kind traditionally given to stars who really should have been recognised by the Academy long ago. In Lansbury's case, few actors can match her lifelong commitment to Hollywood.

Lansbury's career began in 1943, when she signed with MGM. Since then she has taken onroles as diverse as Miss Eglantine Price in Bedknobs and Broomsticks, Rose in Gypsy, a singing teapot in Beauty and the Beast and, perhaps most famously, Jessica Fletcher, the bestselling author and amateur detective from the long-running television series Murder, She Wrote. She played another detective, Agatha Christie's Miss Marple, in 1980's The Mirror Crack'd.

Now aged 88, she is still committed to acting, having starred in an Australian tour of Driving Miss Daisy until June 2013 and spoken of her hopes to return to the West End stage.

But an Oscar has always eluded her. Lansbury has been nominated for an Academy Award three times for supporting performances: for 1944's Gaslight, 1945's The Picture of Dorian Gray and 1962's The Manchurian Candidate. She starred in her first film when she was 18, which gave her her first Oscar nomination, and she's barely stopped working since.

Born in London in 1925, to an Irish actress mother and a father who was a politician, she and her family eventually escaped the Blitz in 1940 by moving to New York City, where Lansbury would later train at the Lucy Fagan school for dramatic art. She had a stable and respected film career for many years before hitting global stardom.

But worldwide fame came for the first time with the popularity of Murder, She Wrote, which began airing in 1984. The combination of cookie-cutter morality figures and neatly tied-up mysteries, all set in picturesque locations (often pastel-coloured New England, but travelling to wherever Fletcher's book tours took her), gained fans all over the world, particularly in America and in Lansbury's native Britain. It also boasted some famous guest stars, including Jenny Agutter, George Clooney, and many more.

The series would run for 12 years, with Lansbury nominated for an Emmy every season – though, mirroring her Oscars track record, she never won. She has, however, picked up a total of five Tony awards.

When it was announced this week that Murder, She Wrote is to be given a contemporary remake by NBC with Octavia Spencer playing Jessica Fletcher, Lansbury was quick to voice her disapproval. "I suddenly became a worldwide-known character as Jessica Fletcher and really built an enormous audience, which I have to this day," she told reporters.

"I think it's a mistake to call it Murder, She Wrote, because Murder, She Wrote will always be about Cabot Cove and this wonderful little group of people who told those lovely stories and enjoyed a piece of that place, and also enjoyed Jessica Fletcher, who is a rare and very individual kind of person," she said.

Lansbury has remained a strong female presence in films and on stage even – and, perhaps, increasingly – as she got older. She told The Telegraph in 2012 that the breakup of her first marriage, to Richard Cromwell when she was just 19, left her heartbroken but hardened: "It made me in a way, a little bit tough. I think it did. I know it did. I said, ‘All right, I’m going to show everyone’.”

Lansbury always insisted that Murder, She Wrote's Jessica Fletcher should remain a strong, single woman with her own interests and adventures in life, and resisted suggestions that her character should fall into a relationship.

But the honorary Oscar should remind audiences (and Lansbury herself) that she is not just known for the TV series. As a talented actor and singer with some of the biggest films of the twentieth century on her CV, she remains one of Hollywood's greatest assets.

"It was quite an emotional moment," she said on hearing that she was to receive her Oscar at last. "It's a nod for everything I've done, in a sense. That's what it means to me. It is really an acknowledgement of a good career, a good career as an actress in Hollywood."

Lansbury's honorary award, along with awards for Steve Martin and Angelina Jolie, is presented tonight as part of the annual Governors' Awards ceremony in Los Angeles.